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Subject: Re: Crafty opening book question

Author: Alvaro Jose Povoa Cardoso

Date: 14:46:57 10/01/01

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On October 01, 2001 at 17:36:26, Robert Hyatt wrote:

>On October 01, 2001 at 16:55:21, Alvaro Jose Povoa Cardoso wrote:
>
>>I know this question was probably made many times, but I wasn't listening :)
>>Could someone please explain in detail the Crafty openings book binary format?
>>Does it represent positions and not moves?
>>
>>Best regards,
>>Alvaro Cardoso
>
>
>Yes.  It is essentially hash signatures produced by making moves and then
>updating the hash signature after each move and storing it.
>
>It uses a cute "grouping" scheme so that all the signatures that share a
>common "parent" position are lumped together in the book file so that one I/O
>operation will read in all possible book moves for any position.

Could you please explain this grouping scheme?

Also, did you ever noticed any anomalies by using the hash signatures scheme
due the non existing 'one to one relation' bettween positions and hash
signatures? In other words, could a program make a wrong opening move because of
hashing inconsistencies/limitations?

Thank you,
Alvaro Cardoso






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